U.S. patent application number 10/975977 was filed with the patent office on 2005-06-30 for method and apparatus for providing individual power control information in a wireless local area network/wireless wide area network (wlan/wwan).
This patent application is currently assigned to InterDigital Technology Corporation. Invention is credited to Chandra, Arty, Hunkeler, Teresa Joanne.
Application Number | 20050143119 10/975977 |
Document ID | / |
Family ID | 34704367 |
Filed Date | 2005-06-30 |
United States Patent
Application |
20050143119 |
Kind Code |
A1 |
Chandra, Arty ; et
al. |
June 30, 2005 |
Method and apparatus for providing individual power control
information in a wireless local area network/wireless wide area
network (WLAN/WWAN)
Abstract
Method and apparatus employed by wireless network components
such as access points (APs) for controlling transmitting power
level of individual wireless transmitter/receiver units (WTRUs) by
establishing a power transmit level based on prior transmit and
receiving transmission and reception statistics such as signal to
noise ratio (SNR), bit error rate (BER), frame error rate (FER)
and/or the like. Power transmit level information is preferably
communicated through any one of a clear to send (CTS), request to
send (RTS), data and acknowledge (ACK) frame. Alternatively the
power control information may be inserted into a beacon frame or an
individual control frame specifically designated for power control.
The WTRUs preferably have battery level sensors and adjust power
control level responsive to a sensed battery level. Alternatively,
the APs and WTRUs may reverse roles and the WTRUs may provide power
transmit level information to an AP to facilitate transmissions by
the AP.
Inventors: |
Chandra, Arty; (Manhasset
Hills, NY) ; Hunkeler, Teresa Joanne; (Montreal,
CA) |
Correspondence
Address: |
VOLPE AND KOENIG, P.C.
DEPT. ICC
UNITED PLAZA, SUITE 1600
30 SOUTH 17TH STREET
PHILADELPHIA
PA
19103
US
|
Assignee: |
InterDigital Technology
Corporation
Wilmington
DE
|
Family ID: |
34704367 |
Appl. No.: |
10/975977 |
Filed: |
October 28, 2004 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60533539 |
Dec 31, 2003 |
|
|
|
Current U.S.
Class: |
455/522 ;
455/343.5; 455/67.11 |
Current CPC
Class: |
H04W 52/288
20130101 |
Class at
Publication: |
455/522 ;
455/067.11; 455/343.5 |
International
Class: |
H04B 007/00 |
Claims
What is claimed is:
1. A method employed by an access point (AP) of a wireless network
to control transmit power of a targeted wireless transmit receive
units (WTRUs), said method comprising: determining a desired power
transmission level for a given WTRU; inserting data reflective of
the determined desired power transmission level along with identity
data of said given WTRU in a communication frame; and transmitting
said communication frame whereby said given WTRU is enabled to
adjust transmission power of wireless signals directed to the
AP.
2. The method of claim 1 wherein the determining of the desired
transmit power level includes utilizing prior transmit and receive
statistics by determining and storing data including at least one
of signal to noise ratio (SNR), bit error rate (BER), frame error
rate (FER), transmit power of signals received from the given WTRU
in addition to prior messages dealing with transmit and receive
power levels.
3. The method of claim 2 wherein the AP has an adjustable antenna
and the determining of the desired transmit power level includes
modifying the desired transmit power level responsive to an
adjustment of said adjustable antenna.
4. The method of claim 1 further comprising: inserting data in
given bits of a physical layer convergence procedure (PLCP) header
to identify the power control information that is being sent in the
frame.
5. The method of claim 1 wherein the inserting data reflective of
the determined desired power transmission level includes inserting
desired power transmission level data in a given number of initial
bytes of a data part of the frame.
6. A method employed by a wireless transmit receive unit (WTRU) in
a wireless network comprising: broadcasting a general power
constraint message to other WTRUs; determining a desired power
transmission level for a given WTRU; inserting data reflective of
the desired power transmission level along with identity data of
said given WTRU in a communication frame; and transmitting said
communication frame whereby said given WTRU is enabled to adjust
transmission power of wireless signals directed to the WTRU
irrespective of the general power constraint message.
7. The method of claim 6 wherein the WTRU is an access point (AP)
of a wireless local area network (WLAN) and broadcasting a general
power constraint message is performed by the AP in beacon
frames.
8. The method of claim 7 wherein the inserting data reflective of
the desired power transmission level includes inserting the desired
power transmission level data into the beacon frames.
9. The method of claim 7 wherein the inserting data reflective of
the desired power transmission level includes inserting the desired
power transmission level data into a clear-to-send (CTS),
request-to-send (RTS), data or acknowledge (ACK) frame.
10. The method of claim 9 further comprising inserting data in
given bits of a physical layer convergence procedure (PLCP) header
to identify the desired power transmission level data that is being
sent in the frame.
11. The method of claim 9 wherein the inserting data reflective of
the desired power transmission level includes inserting the desired
power transmission level data in a given number of the initial
bytes of a data part of the frame.
12. The method of claim 9 wherein the inserting data reflective of
the desired power transmission level includes inserting the desired
power transmission level data in a Medium Access Control (MAC)
header.
13. The method of claim 9 further comprising inserting data
reflective of the AP transmission power level in the communication
frame along with the desired power transmission level and identity
data of said given WTRU.
14. The method of claim 7 wherein determining the desired transmit
power level includes utilizing prior transmit and receive
statistics by determining and storing data including at least one
of signal to noise ratio (SNR), bit error rate (BER) and frame
error rate (FER), transmit power of signals received from the given
WTRU in addition to prior messages dealing with transmit and
receive power levels.
15. The method of claim 7 wherein the inserting data reflective of
the desired power transmission level includes inserting the desired
power transmission level data into an individual control frame
specifically designated for power control.
16. A wireless communication method for a wireless transmit receive
unit (WTRU) in a wireless network comprising: receiving a broadcast
of a general power constraint message from an access point (AP) of
the wireless network; establishing a wireless communication
association with the AP; receiving a communication frame from the
AP having data reflective of a desired power transmission level
along with identity data of the WTRU; and adjusting transmission
power of wireless signals directed to the AP based on the received
desired power transmission level data irrespective of the general
power constraint message.
17. The method of claim 16 wherein the broadcast of a general power
constraint message is received in beacon frames in a wireless local
area network (WLAN).
18. The method of claim 16 wherein the WTRU is powered by a battery
and the adjusting transmission power of wireless signals directed
to the AP further includes: measuring remaining battery energy
capacity; and modifying transmission power based on the received
desired power transmission level data and the measured remaining
energy capacity.
19. The method of claim 18 wherein the adjusting transmission power
of wireless signals directed to the AP includes using the received
desired power transmission level data as a basis for adjustment
when the measured remaining energy capacity of the battery is above
a given threshold.
20. The method of claim 19 wherein the adjusting transmission power
of wireless signals directed to the AP includes using the received
desired power transmission level data as a basis for adjustment and
reducing the adjustment as a function of a difference of the
measured remaining energy capacity and the given threshold when the
measured remaining energy capacity of the battery is below the
given threshold.
21. The method of claim 20 further comprising transmitting a low
battery message to the AP when the power adjustment is reduced.
22. The method of claim 16 further comprising transmitting a
non-conforming adjustment message to the AP when the adjusting
transmission power of wireless signals directed to the AP based on
the received desired power transmission level data is effected by
WTRU determined criteria.
23. The method of claim 22 wherein the adjusting transmission power
of wireless signals directed to the AP based on the received
desired power transmission level data is also based on at least one
WTRU determined criteria from among remaining battery capacity,
maximum power level, minimum power level and unsupported
features.
24. The method of claim 16 further comprising: determining a
desired AP power transmission level for AP transmissions to the
WTRU; inserting data reflective of the desired AP power
transmission level along with identity data of the WTRU in a
communication frame; and transmitting said communication frame
whereby the AP is enabled to adjust transmission power of wireless
signals directed to the WTRU.
25. The method of claim 24 wherein the inserting data reflective of
the desired AP power transmission level includes inserting the
desired AP power transmission level data into a clear-to-send
(CTS), request-to-send (RTS), data or acknowledge (ACK) frame.
26. The method of claim 25 further comprising inserting data in
given bits of a physical layer convergence procedure (PLCP) header
to identify the desired AP power transmission level data that is
being sent in the frame.
27. The method of claim 25 wherein the inserting data reflective of
the desired AP power transmission level includes inserting the
desired power transmission level data in a given number of the
initial bytes of a data part of the frame.
28. The method of claim 25 wherein the inserting data reflective of
the desired AP power transmission level includes inserting the
desired AP power transmission level data in a Medium Access Control
(MAC) header.
29. The method of claim 24 wherein determining the desired AP
transmit power level includes utilizing prior transmit and receive
statistics by determining and storing data including at least one
of signal to noise ratio (SNR), bit error rate (BER) and frame
error rate (FER), transmit power of signals received from the AP in
addition to prior messages dealing with transmit and receive power
levels.
30. The method of claim 24 wherein the inserting data reflective of
the desired AP power transmission level includes inserting the
desired power transmission level data into an individual control
frame specifically designated for power control.
31. A wireless communication method for a wireless transmit receive
unit (WTRU) in a wireless network comprising: receiving a broadcast
of a general power constraint message from an access point (AP) of
a wireless local area network (WLAN); establishing a wireless
communication association with the AP; determining a desired AP
power transmission level for AP transmissions to the WTRU;
inserting data reflective of the desired AP power transmission
level along with identity data of the WTRU in a communication
frame; and transmitting said communication frame whereby the AP is
enabled to adjust transmission power of wireless signals directed
to the WTRU.
32. The method of claim 31 wherein the inserting data reflective of
the desired AP power transmission level includes inserting the
desired AP power transmission level data into a clear-to-send
(CTS), request-to-send (RTS), data or acknowledge (ACK) frame.
33. The method of claim 32 further comprising inserting data in
given bits of a physical layer convergence procedure (PLCP) header
to identify the desired AP power transmission level data that is
being sent in the frame.
34. The method of claim 32 wherein the inserting data reflective of
the desired AP power transmission level includes inserting the
desired power transmission level data in a given number of the
initial bytes of a data part of the frame.
35. The method of claim 32 wherein the inserting data reflective of
the desired AP power transmission level includes inserting the
desired AP power transmission level data in a Medium Access Control
(MAC) header.
36. The method of claim 31 wherein determining the desired AP
transmit power level includes utilizing prior transmit and receive
statistics by determining and storing data including at least one
of signal to noise ratio (SNR), bit error rate (BER) and frame
error rate (FER), transmit power of signals received from the AP in
addition to prior messages dealing with transmit and receive power
levels.
37. The method of claim 31 wherein the inserting data reflective of
the desired AP power transmission level includes inserting the
desired power transmission level data into an individual control
frame specifically designated for power control.
38. A wireless transmit receive unit (WTRU) configured for use in a
wireless network comprising: a transmitter configured to broadcast
general power constraint messages to other WTRUs; a processor
configured to determine a desired power transmission level for a
given WTRU and to insert data reflective of the desired power
transmission level along with identity data of said given WTRU in a
communication frame; and said transmitter configured to transmit
communication frames including desired power transmission level and
identity data to enable said given WTRU to adjust transmission
power of wireless signals directed to the WTRU irrespective of the
general power constraint message.
39. The WTRU according to claim 38 configured as an access point
(AP) of a wireless local area network (WLAN) wherein said
transmitter is configured to broadcast the general power constraint
messages in beacon frames.
40. The AP of claim 39 wherein said processor is configured to
insert data reflective of the desired power transmission level by
inserting the desired power transmission level data into the beacon
frames.
41. The AP of claim 39 wherein said processor is configured to
insert data reflective of the desired power transmission level by
inserting the desired power transmission level data into a
clear-to-send (CTS), request-to-send (RTS), data or acknowledge
(ACK) frame.
42. The AP of claim 41 wherein said processor is configured to
insert data in given bits of a physical layer convergence procedure
(PLCP) header to identify the desired power transmission level data
that is being sent in the frame.
43. The AP of claim 41 wherein said processor is configured to
insert data reflective of the desired power transmission level by
inserting the desired power transmission level data in a given
number of the initial bytes of a data part of the frame.
44. The AP of claim 41 wherein said processor is configured to
insert data reflective of the desired power transmission level by
inserting the desired power transmission level data in a Medium
Access Control (MAC) header.
45. The AP of claim 41 wherein said processor is configured to
insert data reflective of the AP transmission power level in the
communication frame along with the desired power transmission level
and identity data of said given WTRU.
46. The AP of claim 39 wherein said processor is configured to
determine the desired transmit power level by utilizing prior
transmit and receive statistics by determining and storing data
including at least one of signal to noise ratio (SNR), bit error
rate (BER) and frame error rate (FER), transmit power of signals
received from the given WTRU in addition to prior messages dealing
with transmit and receive power levels.
47. The AP of claim 39 wherein said processor is configured to
insert data reflective of the desired power transmission level by
inserting the desired power transmission level data into an
individual control frame specifically designated for power
control.
48. A wireless transmit receive unit (WTRU) for use in a wireless
network comprising: a receiver configured to receive a broadcast of
a general power constraint message from an access point (AP) of the
wireless network; said receiver further configured to receive a
communication frame from the AP having data reflective of a desired
power transmission level along with identity data of the WTRU; and
a transmitter having an associated processor configured to adjust
transmission power of wireless signals directed to the AP based on
the received desired power transmission level data irrespective of
the general power constraint message.
49. The WTRU of claim 48 wherein receiver is configured to receive
the broadcast of general power constraint messages in beacon frames
in a wireless local area network (WLAN).
50. The WTRU of claim 49 further comprising a battery to provide
electric power and wherein said processor is configured to adjust
transmission power of wireless signals directed to the AP by
measuring remaining battery energy capacity and modifying
transmission power based on the received desired power transmission
level data and the measured remaining energy capacity.
51. The WTRU of claim 50 wherein said processor is configured to
adjust transmission power of wireless signals directed to the AP by
using the received desired power transmission level data as a basis
for adjustment when the measured remaining energy capacity of the
battery is above a given threshold.
52. The WTRU of claim 51 wherein said processor is configured to
adjust transmission power of wireless signals directed to the AP by
using the received desired power transmission level data as a basis
for adjustment and reducing the adjustment as a function of a
difference of the measured remaining energy capacity and the given
threshold when the measured remaining energy capacity of the
battery is below the given threshold.
53. The WTRU of claim 52 wherein said transmitter is configured to
transmit a low battery message to the AP when the power adjustment
is reduced.
54. The WTRU of claim 48 wherein said transmitter is configured to
transmit a non-conforming adjustment message to the AP when said
processor's adjustment of transmission power of wireless signals
directed to the AP based on the received desired power transmission
level data is effected by WTRU determined criteria.
55. The WTRU of claim 54 wherein said processor is configured to
adjust transmission power of wireless signals directed to the AP
based on the received desired power transmission level data and
based on at least one WTRU determined criteria from among remaining
battery capacity, maximum power level, minimum power level and
unsupported features.
56. The WTRU of claim 48 wherein said processor is configured to
determine a desired AP power transmission level for AP
transmissions to the WTRU and to insert data reflective of the
desired AP power transmission level along with identity data of the
WTRU in a communication frame and wherein said transmitter is
configured to transmit said communication frame whereby the AP is
enabled to adjust transmission power of wireless signals directed
to the WTRU.
57. The WTRU of claim 56 wherein said processor is configured to
insert data reflective of the desired AP power transmission level
by inserting the desired AP power transmission level data into a
clear-to-send (CTS), request-to-send (RTS), data or acknowledge
(ACK) frame.
58. The WTRU of claim 57 wherein said processor is configured to
insert data in given bits of a physical layer convergence procedure
(PLCP) header to identify the desired AP power transmission level
data that is being sent in the frame.
59. The WTRU of claim 57 wherein said processor is configured to
insert data reflective of the desired AP power transmission level
by inserting the desired power transmission level data in a given
number of the initial bytes of a data part of the frame.
60. The WTRU of claim 57 wherein said processor is configured to
insert data reflective of the desired AP power transmission level
by inserting the desired AP power transmission level data in a
Medium Access Control (MAC) header.
61. The WTRU of claim 56 wherein said processor is configured to
determine the desired AP transmit power level by utilizing prior
transmit and receive statistics by determining and storing data
including at least one of signal to noise ratio (SNR), bit error
rate (BER) and frame error rate (FER), transmit power of signals
received from the AP in addition to prior messages dealing with
transmit and receive power levels.
62. The WTRU of claim 56 wherein said processor is configured to
insert data reflective of the desired AP power transmission level
by inserting the desired power transmission level data into an
individual control frame specifically designated for power
control.
63. A wireless transmit receive unit (WTRU) for use in a wireless
network comprising: a receiver configured to receive a broadcast of
a general power constraint message from an access point (AP) of the
wireless network; a processor configured to determine a desired AP
power transmission level for AP transmissions to the WTRU and to
insert data reflective of the desired AP power transmission level
along with identity data of the WTRU in a communication frame; and
a transmitter configured to transmit said communication frame
whereby the AP is enabled to adjust transmission power of wireless
signals directed to the WTRU.
64. The WTRU of claim 63 wherein said processor is configured to
insert data reflective of the desired AP power transmission level
by inserting the desired AP power transmission level data into a
clear-to-send (CTS), request-to-send (RTS), data or acknowledge
(ACK) frame.
65. The WTRU of claim 64 wherein said processor is configured to
insert data in given bits of a physical layer convergence procedure
(PLCP) header to identify the desired AP power transmission level
data that is being sent in the frame.
66. The WTRU of claim 64 wherein said processor is configured to
insert data reflective of the desired AP power transmission level
by inserting the desired power transmission level data in a given
number of the initial bytes of a data part of the frame.
67. The WTRU of claim 64 wherein said processor is configured to
insert data reflective of the desired AP power transmission level
by inserting the desired AP power transmission level data in a
Medium Access Control (MAC) header.
68. The WTRU of claim 63 wherein said processor is configured to
determine the desired AP transmit power level by utilizing prior
transmit and receive statistics by determining and storing data
including at least one of signal to noise ratio (SNR), bit error
rate (BER) and frame error rate (FER), transmit power of signals
received from the AP in addition to prior messages dealing with
transmit and receive power levels.
69. The WTRU of claim 63 wherein said processor is configured to
insert data reflective of the desired AP power transmission level
by inserting the desired power transmission level data into an
individual control frame specifically designated for power control.
Description
CROSS REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims the benefit of U.S. provisional
application No. 60/533,539, filed Dec. 31, 2003, which is
incorporated by reference as if fully set forth.
FIELD OF INVENTION
[0002] The present invention relates to wireless local area
networks/wireless wide area networks (WLANs/WWANs) and more
particularly to method and apparatus for use in WLANs/WWANs to
provide individualized power information.
BACKGROUND
[0003] Wireless communication systems are well known in the art.
Generally, such systems comprise communication stations, which
transmit and receive wireless communication signals between each
other. Depending upon the type of system, communication stations
typically are one of two types of wireless transmit/receive units
(WTRUs): base stations or subscriber units, which include mobile
units.
[0004] The term base station as used herein includes, but is not
limited to, a base station, Node B, site controller, access point
or other interfacing device in a wireless environment that provides
WTRUs with wireless access to a network with which the base station
is associated.
[0005] The term WTRU as used herein includes, but is not limited
to, a user equipment, mobile station, fixed or mobile subscriber
unit, pager, or any other type of device capable of operating in a
wireless environment. WTRUs include personal communication devices,
such as phones, video phones, and Internet ready phones that have
network connections. In addition, WTRUs include portable personal
computing devices, such as PDAs and notebook computers with
wireless modems that have similar network capabilities. WTRUs that
are portable or can otherwise change location are referred to as
mobile units. Generically, base stations are also WTRUs.
[0006] Typically, a network of base stations is provided where each
base station is capable of conducting concurrent wireless
communications with appropriately configured WTRUs. Some WTRUs are
configured to conduct wireless communications directly between each
other, i.e., without being relayed through a network via a base
station. This is commonly called peer-to-peer wireless
communications. Where a WTRU is configured communicate with other
WTRUs it may itself be configured as and function as a base
station. WTRUs can be configured for use in multiple networks with
both network and peer-to-peer communications capabilities.
[0007] One type of wireless system, called a wireless local area
network (WLAN), can be configured to conduct wireless
communications with WTRUs equipped with WLAN modems that are also
able to conduct peer-to-peer communications with similarly equipped
WTRUs. Currently, WLAN modems are being integrated into many
traditional communicating and computing devices by manufacturers.
For example, cellular phones, personal digital assistants, and
laptop computers are being built with one or more WLAN modems.
[0008] Popular WLAN environments with one or more WLAN base
stations, typically called access points (APs), are built according
to the IEEE 802.11 standards. Access to these networks usually
requires user authentication procedures. Protocols for such systems
are presently being standardized in the WLAN technology area. One
such framework of protocols is the IEEE 802 family of
standards.
[0009] A basic service set (BSS) is the basic building block of an
IEEE 802.11 WLAN and this consists of WTRUs also referred to as
stations (STAs). Basically, the set of WTRUs which can talk to each
other can form a BSS. Multiple BSSs are interconnected through an
architectural component, called distribution system (DS), to form
an extended service set (ESS). An access point (AP) is a WTRU that
provides access to DS by providing DS services and generally allows
concurrent access to DS by multiple WTRUs.
[0010] A network of WTRUs operating with peer to peer
communications in an IEEE 802.11 environment, typically referred to
as "ad hoc" mode, is called "independent BSS". In an "independent
BSS", two or more WTRUs establish a communication among themselves
without the need of a coordinating network element. There are no AP
to network infrastructure required. However, an AP can be
configured with the ad hoc protocols to act as the other WTRUs in
peer to peer communications. In such case an AP may act as a bridge
or router to another network or to the Internet.
[0011] The WTRU that starts an ad hoc network selects the ad hoc
network's operating parameters, such as the service set identifier
(SSID), channel and beacon timing, and the transmits this
information in, for example, Beacon frames. As stations join the ad
hoc network, they assimilate the operating parameters. Where
network infrastructure is used and wireless communications are
controlled through APs, parameters such as the SSID are normally
specified by a network controller connected to APs which
periodically broadcast a beacon frame to enable WTRUs to identify
the AP and attempt to establish communications.
[0012] The SSID in a IEEE 802 based system can be a 32-character
unique identifier attached to a header of packets sent over a WLAN.
The SSID then acts as a password when a WTRU attempts to connect to
a BSS or an independent BSS. The SSID differentiates one WLAN from
another, so all base stations and all devices attempting to connect
to a specific WLAN normally use the same SSID. A device will not
normally be permitted to join a BSS unless it can provide the
unique SSID.
[0013] On a broader scale a wireless wide area network (WWAN) can
be provided to support communications between APs or other types of
network base stations and user WTRUs. Cellular networks operating
over great distances are one type of WWAN.
[0014] Typically, APs provided in WLANs/WWANs broadcast power
constraint information which is utilized by all WTRUs communicating
with an AP to reduce transmit power. The inventors have recognized
that it would be desirable to provide for reducing/increasing
transmit power of each WTRU and/or other connection or device,
individually.
SUMMARY
[0015] The present invention is characterized by comprising method
and apparatus for use in wireless local area networks/wireless wide
area networks (WLANs/WWANs) capable of providing transmit power
information to individual wireless transmit/receive units
(WTRUs).
[0016] A transmit power level is preferably established based on
prior transmission and reception statistics such as signal to noise
ration (SNR), bit error rate (BER), frame error rate (FER) and/or
the like. The desired power transmit information is preferably
communicated to a particular WTRU in a header of any one of a
clear-to-send (CTS), request-to-send (RTS), data or acknowledge
(ACK) frame that designated for that WTRU. The computation of the
power level and transmission of power transmit information may be
done at an AP for controlling the transmission power of a WTRU with
which the AP is communicating or at a WTRU for controlling the
transmission power of frames from an AP that are directed to the
WTRU.
[0017] The individual transmit power information can optionally by
conveyed by an AP through a beacon frame which is adapted to
include both WTRU identities and power control data of the targeted
WTRUs, preferably in addition to an initial power control setting
for use by WTRUs when first initiating communications.
Alternatively, a specifically designated for power control frame is
provided in which the power control information is inserted.
However, it is preferable to communicate the power control
information in a frame that is also used for other purposes in
order not to adversely effect network throughput.
[0018] In one aspect of the invention, a wireless transmit receive
unit (WTRU) has a transmitter configured to broadcast general power
constraint messages to other WTRUs and an associated processor. The
processor is preferably configured to determine a desired power
transmission level for a given WTRU and to insert data reflective
of the desired power transmission level along with identity data of
said given WTRU in a communication frame. The transmitter is
preferably configured to transmit communication frames including
desired power transmission level and identity data to enable said
given WTRU to adjust transmission power of wireless signals
directed to the WTRU irrespective of the general power constraint
message. Preferably such a WTRU is configured as an access point
(AP) of a wireless local area network (WLAN) having its transmitter
configured to broadcast the general power constraint messages in
beacon frames.
[0019] The processor of such an AP may be configured to insert data
reflective of the desired power transmission level by inserting the
desired power transmission level data into the beacon frames.
Alternatively the processor can be configured to insert data
reflective of the desired power transmission level by inserting the
desired power transmission level data into standard clear-to-send
(CTS), request-to-send (RTS), data or acknowledge (ACK) frames or
into an individual control frame specifically designated for power
control.
[0020] Additionally, the AP processor may be configured to insert
data in given bits of a physical layer convergence procedure (PLCP)
header to identify the desired power transmission level data that
is being sent in the frame.
[0021] Other alternatives include, the AP processor being
configured to insert data reflective of the desired power
transmission level by inserting the desired power transmission
level data in a given number of the initial bytes of a data part of
the frame or by inserting the desired power transmission level data
in a Medium Access Control (MAC) header. The AP processor may also
be configured to insert data reflective of the AP transmission
power level in the communication frame along with the desired power
transmission level and identity data of said given WTRU.
[0022] Preferably, the AP processor is configured to determine the
desired transmit power level by utilizing prior transmit and
receive statistics by determining and storing data including at
least one of signal to noise ratio (SNR), bit error rate (BER) and
frame error rate (FER), transmit power of signals received from the
given WTRU in addition to prior messages dealing with transmit and
receive power levels.
[0023] In another aspect of the invention, a WTRU is configured for
use in a wireless network with a receiver, a transmitter and an
associated processor. The receiver is preferably configured to
receive a broadcast of a general power constraint message from an
access point (AP) of the wireless network. The receiver is
preferably further configured to receive a communication frame from
the AP having data reflective of a desired power transmission level
along with identity data of the WTRU. The processor is preferably
configured to adjust transmission power of wireless signals
directed to the AP based on the received desired power transmission
level data irrespective of the general power constraint message.
The WTRU's receiver is preferably configured to receive the
broadcast of general power constraint messages in beacon frames in
a wireless local area network (WLAN).
[0024] The WTRU's transmitter can be configured to transmit a
non-conforming adjustment message to the AP when the processor's
adjustment of transmission power of wireless signals directed to
the AP based on the received desired power transmission level data
is effected by WTRU determined criteria. In such case, the WTRU's
processor is preferably configured to adjust transmission power of
wireless signals directed to the AP based on the received desired
power transmission level data and based on at least one WTRU
determined criteria from among remaining battery capacity, maximum
power level, minimum power level and unsupported features.
[0025] Where the WTRU includes a battery to provide electric power,
the processor can be configured to adjust transmission power of
wireless signals directed to the AP by measuring remaining battery
energy capacity and modifying transmission power based on the
received desired power transmission level data and the measured
remaining energy capacity. In such case, the processor is
preferably configured to adjust transmission power of wireless
signals directed to the AP by using the received desired power
transmission level data as a basis for adjustment when the measured
remaining energy capacity of the battery is above a given threshold
and by using the received desired power transmission level data as
a basis for adjustment and reducing the adjustment as a function of
a difference of the measured remaining energy capacity and the
given threshold when the measured remaining energy capacity of the
battery is below the given threshold. The WTRU's transmitter can
then be configured to transmit a low battery message to the AP when
the power adjustment is reduced.
[0026] The WTRU's processor can also be configured to determine a
desired AP power transmission level for AP transmissions to the
WTRU and to insert data reflective of the desired AP power
transmission level along with identity data of the WTRU in a
communication frame. In such case, the transmitter is configured to
transmit the communication frame whereby the AP is enabled to
adjust transmission power of wireless signals directed to the WTRU.
Preferably, the WTRU's processor is configured to insert data
reflective of the desired AP power transmission level by inserting
the desired AP power transmission level data into a clear-to-send
(CTS), request-to-send (RTS), data or acknowledge (ACK) frame or an
individual control frame specifically designated for power control.
Similarly, such a WTRU's processor can be configured to insert data
as discussed above for the example of an AP's processor.
[0027] Although the features and elements of the present invention
are described in the preferred embodiments in particular
combinations, each feature or element can be used alone (without
the other features and elements of the preferred embodiments) or in
various combinations with or without other features and elements of
the present invention.
BRIEF DESCRIPTION OF THE DRAWING(S)
[0028] The present invention will be understood from consideration
of the drawings in which like elements are designated by like
numerals and, wherein:
[0029] FIG. 1 is a simplified block diagram of a WLAN network.
[0030] FIG. 2 is a schematic diagram showing an example of the
manner in which an AP generates and sends power transmit
information.
[0031] FIG. 3 is a schematic diagram showing the manner in which a
WTRU adjusts its power transmit output responsive to power transmit
information from an AP and the battery consumption of the WTRU.
[0032] FIG. 4 is a schematic diagram showing an example of the
manner in which a WTRU generates and sends power transmit
information.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0033] FIG. 1 shows a wireless local area network/wireless wide
area network (WLAN/WWAN) 10 comprised of at least one AP and a
plurality of wireless transmit/receive units (WTRUs), WTRU-1
through WTRU-N, communicating therewith. Each AP is capable of
transmitting power information to WTRUs within its communication
range and each WTRU is likewise capable of transmitting power
information to APs within its communication range.
[0034] In existing standards, such as the IEEE 802.11h standard
(Section 7.3.2.1.3), a local power constraint element is sent in a
beacon frame by all APs. This local power constraint presently in
use sets the transmit power of all WTRUs to the same value. The
present invention distinguishes therefrom and is unique in
providing individual transmit power value to each WTRU particularly
in the context of WLANs/WWANs configured to operate in compliance
with the IEEE 802.11 standards.
[0035] FIG. 2 illustrates a method and apparatus of the present
invention employed by an access point (AP) of one of a WLAN or
WWAN. At step S1, the AP determines a power level for a given
remote WTRU, the power level being based on prior transmission and
reception statistics utilizing information such as signal to noise
ration (SNR), bit error rate (BER), frame error rate (FER) and/or
the like. At step S2, the AP preferably inserts power level data
power constraint message for the given WTRU in a frame header of a
frame such as a clear-to send (CTS), request-to send (RTS), data or
acknowledgment (ACK) frame that is directed to the specific WTRU.
The AP, at step S3, transmits the frame that includes the power
level data. The transmit power level data may take the form of a
power constraint message and/or may be actual transmit power, a
transmit power amount lower than a maximum power or higher than a
minimum power or an increase/decrease from the last transmitted
transmit power.
[0036] As one example, in a physical layer convergence procedure
(PLCP) header, eight (8) bits are reserved for service. These bits
are employed to indicate that power control information is sent in
the frame. A first few bytes of the data part of the frame are
employed to send the power control information. The AP is
preferably configured to transmit such frames with power control
information, and the WTRUs are preferably configured to receive
such frames and detect the power control information in such a
frame.
[0037] Preferably, the AP is configured to compute a transmit power
level of an individual WTRU during single or multiple frame
exchange. Also, the AP is preferably configured to communicate the
data representing the computed power transmit level directly to the
individual WTRU, apart from any generally transmitted beacon
frame.
[0038] The individual transmit power data can optionally be
inserted by an AP into a beacon frame which is adapted to include
both WTRU identities and power control data of targeted WTRUs with
which the AP is communicating. Irrespective of whether this option
is used, the AP is preferably configured to broadcast beacon frames
that include an initial power control setting for use by WTRUs when
first initiating communications. Correspondingly, the WTRUs are
preferably configured to only use the initial power control setting
of received beacon frames, if the WTRU has not received individual
transmit power data from the AP.
[0039] Alternatively, a specifically designated for power control
frame is provided in which the power control information is
inserted. However, it is preferable to communicate the power
control information in a frame that is also used for other purposes
in order not to adversely effect network throughput.
[0040] APs having a smart or adaptable antenna capability can use
the present invention to great advantage which enables use of lower
power control information due to the enhanced ability of the AP
antenna, which capability, when present, factors into the
transmission (TX) characteristics.
[0041] In addition WTRUs are provided with a power control
algorithm to adjust power level taking into account battery
consumption as well as the power control information from the
AP.
[0042] A preferred operational configuration for a WTRU employing
the teachings of the invention is illustrated in FIG. 3. The WTRU,
after receiving a designated frame that includes the power transmit
information, at step S1, extracts the power level message, at S2,
and, at step S3, measures battery consumption. The WTRU, at step
S4, is preferably configured to adjusts its transmitting power
level taking into account both the received power transmit
information and battery related data which it measures. Prefeably,
the WTRU, at step S4, uses the transmit power level derived from
the AP, but reduces that power level when the measured battery
level is below a given threshold. The amount of reduction of the
transmit power level is preferably calculated as a function of
increasingly lower battery level below the threshold. The results
of the adjustments made, at step S4, are stored, at step S5, for
use in future power level adjustments.
[0043] A noted above, a WTRU may provide a power level data to an
AP to control the power of the transmissions of the AP directed to
that WTRU. A preferred operational configuration for such a WTRU is
illustrated in FIG. 4. The WTRU, at step S6, measures battery
consumption. At step S7 the WTRU determines a power level based on
prior reception data including one or more of BER, FER, SNR, etc,
but modifies this information to increase the determined power
level when the measured battery level is below a given threshold.
Corresponding power level data is then sent to the AP, at step S8.
The AP uses this information in determining power level for
communications with the WTRU. The AP can also use this information
in determining its transmission power for communications with other
WTRUs and/or in computing power level data to be sent to WTRUs to
control their repective transmission powers.
[0044] In order to perform the functions described above, the WTRU
is configured with apparatus incorporating a receiver having an
antenna configured to receive the defined frames transmitted by the
AP. Where modulated signals are transmitted, the receiver is
preferably configured with a demodulator to reduce the received
signals to baseband. The WTRU is further preferably configured with
apparatus to extract the targeted power constraint signal. For
battery operated WTRUs, a sensor is preferably provided that is
configured to measure energy capacity of the WTRU battery
source.
[0045] The WTRU also preferably includes a transmitter having an
adjustable transmission power level and a controller configured to
set the power transmission level based upon either a received power
constraint message taken alone, or a power constraint message
modified according to energy capacity of a portable power source
when such infomation is available. The controller may further be
configured to modify the power level adjustment to one of a
plurality of levels based upon the magnitude of the difference
between maximum energy capacity remaining in a battery source and
measured energy capacity or the difference between a preset
threshold and measured energy capacity.
[0046] The WTRU controller is preferably configured to store
measured energy capacity reading and generate a power level message
which is forwarded to an AP as part of an RTS or ACK frame. The
WTRU receiver may further be configured to measure power level of a
beacon frame, which reading is then stored. The WTRU controller is
then preferably configured to provide the transmitter with the
measured power level as part of or in addition to the power level
in WTRU identification message transmitted to the AP.
[0047] The AP is preferably configured with a receiver for
receiving the WTRU message and converting the message to baseband.
An AP controller is preferably configured to generate a power level
constraint message based upon information in messages received from
a WTRU and previously stored source data and provide power level
data in the form of a power constraint message to an AP
transmitter.
[0048] The AP is further preferably configured to insert the power
constraint message into one of a CTS, RTS, ACK, or data frame and
to insert data into a PLCP header to identify the power constraint
message that is being sent in the frame along with an identity code
to identify the WTRU intended to receive the frame and associated
power constraint message.
[0049] The WTRUs and APs may reverse roles and the WTRUs may
utilize the techniques set forth above to provide information
equivalent to a power constraint message to aid the AP in its
transmissions.
[0050] Although the features and elements of the present invention
are described in the preferred embodiments in particular
combinations, each feature or element can be used alone (without
the other features and elements of the preferred embodiments) or in
various combinations with or without other features and elements of
the present invention.
* * * * *